Frequently people who are old or ill live alone. When such a person is suddenly striken with an affliction that prevents him from summoning help, he can die, whereas reasonably prompt help could save him. Such afflictions as a stroke, a fall which causes a broken pelvis, or a diabetic coma which are not fatal in themselves become fatal because days or even weeks may pass before the affliction is discovered.
This problem has been dealt with in the past with devices which sense human physical activity and sound an alarm if such physical activity is not sensed for a long time period. Many of these devices must be worn, for example, on the wrist of the user, and forgetting to put such devices on before going to bed or after bathing will cause the alarm to ring when no problem exists. Other devices must be unplugged if the occupant of the premises is to be away on a visit for a long period of time. Everyone, and particularly older persons, are likely to forget to wear an alarm or to unplug it before leaving with the result that disturbing false alarms are sounded.